1. Field of the Invention
This invention relates to a specimen collection container assembly and more particularly to a collection container for collecting biological fluid specimens where a small quantity of fluid may be collected and retained in the container while maintaining a container size sufficient to be easily accommodated and/or compatible with standard clinical equipment and instrumentation.
2. Description of Related Art
Blood samples and other biological fluid specimens are routinely taken and analyzed in hospital and clinical situations for various medical purposes. Collection, handling and testing of these samples typically requires the use of various medical testing instruments. As the blood and fluid specimens are usually collected in a standard sized collection tube, the medical instruments used to test the samples are designed to accommodate these standard sized collection tubes.
Conventional blood collection tubes used in most clinical situations are elongated cylindrical containers having one end closed by a semi-spherical or rounded portion and an opposed open end. The open end may be sealed by a resilient cap or stopper. The tube defines a collection interior which collects and holds the blood sample. The most common size of these blood collection tubes are designed to accommodate approximately 6-10 ml of blood or other biological fluid samples. Illustrative of such blood collection tubes is the VACUTAINER.RTM. brand blood collection tube sold by Becton, Dickinson and Company, 1 Becton Drive, Franklin Lakes, N.J. (registered trademark of Becton, Dickinson and Company).
A phlebotomist or other medical technician typically obtains a specimen of the patient's blood in the tube by techniques well known in the art. The tube is then appropriately labeled and transferred from the site of collection to a laboratory or other location where the contents of the tube are analyzed. During collection and analysis the tube may be supported by various medical instruments. The plasma or serum derived therefrom is processed and analyzed either manually, semi-automatically or automatically. In some cases, the specimen must first be dispensed from the collection tube to a sample test tube or cuvette.
In certain situations it is only necessary to obtain a small quantity of blood or other biological fluid specimens. These situations may include pediatric, or geriatric patients and other instances where large blood samples are not required. Small quantities of blood cannot be easily collected in standard collection tubes as described above because the sample level in such containers would not be adequate for retrieval prior to analysis. Such small quantities of fluids also have a tendency to significantly evaporate when stored in larger containers, thus concentrating the chemical and enzymatic constituents therein. This may result in erroneous analytical results and could possibly affect the diagnosis and treatment given the patient. Therefore, it is desirable to employ small-volume containers which substantially inhibit evaporation for the storage and delivery of minute fluid samples in the laboratory.
Various specimen containers such as those incorporating a "false bottom" have been proposed to achieve decreased volume capacity in conjunction with standard external dimensions. However, these various specimen containers are not compatible with standard clinical equipment and instrumentation due to their design. In particular, these specimen containers have false bottoms with a generally flat, planar bottom end and a circular shaped opening.
Other specimen containers include partial-draw tubes which have standard external dimensions with partial evacuation so that blood fills only a portion of the internal volume. However, partial-draw tubes exhibit a reduction in the draw rate of a sample which reduces the collection efficiency of such tubes. In addition, partial-draw tubes may result in an inconsistent fill volume which may alter test results. Furthermore, it is difficult to determine accurate sample quantities with such partial-draw tubes because the slow rate of sample draw is not consistently measurable.
In clinical use, it is desirable for such specimen collection containers to have rounded bottom configurations that closely simulate a standard-sized blood collection tube configuration instead of planar bottoms. Rounded bottom configurations facilitate compatibility with clinical equipment and instrumentation.
Therefore there is a need to provide a specimen collection container assembly for collecting blood samples and other biological fluid specimens of relatively small volumes where the assembly may be accommodated and/or compatible with standard clinical equipment and/or instrumentation and where the integrity of the sample and specimens are maintained during draw, storage and transport.